Explanation
Use "because" before a full clause. Use "because of" before a noun or noun phrase.
Look at "I stayed home because it was raining." "I stayed home" is the main part of the sentence. "because" gives the reason, and "it was raining" is a full clause with a subject and a verb. In Japanese, one word like "〜から" can cover both forms, but English must match the word after the reason phrase. For example, say "She was late because of the traffic." Here "the traffic" is a noun phrase, so "because of" is correct.
"because" の後ろには、主語と動詞がある文を置きます。"because of" の後ろには、名詞や名詞句を置きます。
例えば "I stayed home because it was raining." では、"I stayed home" が主文です。"because" が理由を示し、その後ろの "it was raining" は主語と動詞を持つ文です。日本語では「〜から」でどちらも言えますが、英語では後ろに文が来るか、名詞が来るかで使い分けます。たとえば "She was late because of the traffic." では、"the traffic" が名詞句なので "because of" を使います。
Examples
- I stayed home because it was raining. 雨が降っていたので、家にいました。
- She was late because of the traffic. 彼女は渋滞のせいで遅れました。
- Why are you late? I was late because the train was delayed. どうして遅れたのですか。電車が遅れたので遅れました。
- We did not go out because of the cold wind. 冷たい風のせいで、外に出ませんでした。
- He bought new shoes because his old ones were too small. 古い靴が小さすぎたので、彼は新しい靴を買いました。
- The game was canceled because of heavy rain. 大雨のため、試合は中止になりました。
Common Mistakes
Japanese learners often say "Because of it was raining, I stayed home." This is wrong because "because of" must come before a noun, not a full clause. Say "I stayed home because it was raining." or "I stayed home because of the rain."
日本人学習者は "Because of it was raining, I stayed home." のように、"because of" の後ろに文を置きがちです。"because of" の後ろは名詞で、文を続けるなら "because" を使います。正しくは "I stayed home because it was raining." または "I stayed home because of the rain." です。